In many instances it is not economical to pump oil from an oilwell using conventional means such as prior art sucker rod pumps or centrifugal pumps. There has long been a need for an automatic pumping unit which can utilize a bail bucket to lift oil from a rather shallow location to the surface. There has been certain apparatus developed for this purpose, but none of them fully as satisfactory as the present invention. U.S. Pat. Nos. 4,037,662 and 4,086,035 are generally illustrative of the state of the art with respect to bailer type pumps for oil wells over which the present invention is considered an improvement.
It is therefore an object of this invention to provide an improved oil well bailer pump or apparatus which overcomes the disadvantages of prior art devices and which provides a substantial step forward in the art with respect to this type of pumping operation.
Briefly stated, the invention includes an elongated housing adapted for mounting on the top of the wellhead of the well to be bailed. A pulley is rigidly supported on an upper portion of the housing for supporting a cable thereon. Seal means are provided for sealing the upper end of the housing against escape of fluid such as free gases or casing gas, if needed. The bail bucket is arranged for up and down movement between the housing and well for raising oil from the bottom of the well to the housing. A cable is connected to the upper portion of the bail bucket and passes upwardly through the seal means and over the pulley for raising and lowering the bail bucket in the well to thereby lift oil to the housing. Means are provided for selectively paying out and taking up the cable to effect alternate raising and lowering of the bail bucket in the well. The invention also includes valve means connected to a lower portion of the housing for normally sealingly closing the housing to prevent escape of fluids such as free gas therefrom and to permit passage of the bail bucket therethrough and which valve means is movable to an open position to divert oil from the housing.
The invention also includes operator means associated with the bail bucket and the housing for moving the valve means to the open position and dumping oil from the bail bucket incident to the arrival of the bucket at the end of the upper travel thereof in said housing.
Certain embodiments of the invention may include means to prevent excessive flexing of the cable at its point of attachment to the bucket. Thus, there is provided a connecting bushing connected to an upper portion of the bucket and having a portion of the cable movably extending downwardly therethrough. Stop means are fixedly attached to the cable at a point below the connection bushing for engaging the connection bushing and thereby limiting movement of the cable upward relative thereto. Spring means in the form of a tension spring is connected between the stop means and a portion of the bucket for exerting a downward biasing force on the cable relative to the bucket to take up slack in the cable when the bucket contacts oil in the well on the downward travel of the bucket.
The operator means may also include a valve member mounted near the bottom of the bucket and arranged for closing the bottom of the bucket in the down position and opening the bottom of said bucket in the raised position, together with an operator rod connected to the valve member and extending upwardly in the bucket. There is also included a pivotal rocker arm connected to an upper part of the bucket and having one end attached to the operator rod for raising and lowering the same during pivoting thereof. A striker pin is connected to the other end of the rocker arm and extends upwardly from the upper end of the bucket, with the upper end of the said striker pin being arranged to be contacted and depressed when the bucket nears the end of the upper travel thereof in the housing, whereby the pin is depressed and the operator rod is raised, thereby moving the valve member to the open position to dump oil from the bucket.
Certain embodiments of the invention may also include a vertically movable striker plate supported in the upper portion of the housing for contact by the striker pin. At least one polished rod is connected to the plate for vertical movement therewith and which rod extends through the upper end of the housing in sealed relationship therewith. This embodiment also includes means for connecting the polished rod to the valve means externally of the housing to move the valve means to the open position coincident with the arrival of the bucket at the upper end of the housing.